Abstract: The light beam in an obstruction detector is coded into packets of pulses by a transmitter according to a code generated only by the transmitter. When the light beam is received, the receiver recovers the code signal and supplies it to a code detection circuit. In one preferred embodiment, to detect the code, the code detection circuit supplies the code signal and a delayed version of the code signal to an "exclusive or" gate. In another embodiment, a frequency detection circuit determines whether the code signal detected by the receiver is within a predetermined permissible range. If the code is not present, the door operator system reverses the door if it is closing, and prevents the door from closing if it already is in the up position, or if it is opening. The door operator system will operate in this way not only in response to obstructions, but also, in response to errors and malfunctions in the wiring to the transmitter and receiver, and in the transmitter and receiver themselves.

Abstract: A door operation control system has a door opening for moving a door between open and closed positions. A door operator control circuit selectively operates the drive means to move the door between the open and closed positions. An obstruction detection device detects whether there is an obstruction in the path of the door between the open and closed positions and generates a signal in response thereto. The obstruction detection device is connected to the control circuit by wiring to permit operation of the door opener in the absence of a signal from the obstruction detection device and to prevent certain operations of the door opener in the presence of a signal from the obstruction detection device. An error detection circuit detects faults or errors in the wiring and generates a signal to prevent certain operations of the door operator when the faults or errors are detected.

Abstract: A door operator for a reversibly operable door includes a frame and a carriage movably mounted on the frame and attached to a door for moving the door between open and closed positions. A drive member, specifically a roller chain, extends along the frame and moves the carriage. A drive train is provided within a housing and is connected for moving the drive member, and a control circuit is provided for controlling the drive train to open and close the door. A pair of limit switches is mounted within the housing and connected to the control circuit for stopping the drive train when the door has reached a completed position. A pair of limit cams are adjustably mounted on a limit wheel within the housing and separate from the carriage for engaging the limit switches. The limit wheel, which is separate from the drive member, is connected to the drive train to rotate when the drive train moves the carriage.

Abstract: A light beam transmitter and receiver are located in or near a door opener enclosure, and fiber optics connect the transmitter and receiver to the sides of the door opening. Lens arrangements are attached to the ends of the optic cables and are mounted near the bottom of the door frame. Thus, the transmitter and receiver do not need to be located near the door which eliminates the need for wiring from the enclosure to the door area and protects the transmitter and detector from physical abuse at the doorway.

Abstract: A door operator for a reversibly operable door, such as a garage door includes a frame, a motor on the frame, a flexible drive member connected to the motor, and a carriage is mounted for movement along the frame. The carriage moves generally parallel to a portion of the frame and is attached to the door to open and close the door by movement of the carriage along the frame. The carriage can be selectively engaged and disengaged from the flexible drive member using an actuating member extending from the carriage. The carriage and the flexible drive member are engaged and disengaged upon successive motions of the actuating member in a direction substantially perpendicular to the direction of travel of the carriage.

Abstract: A door operator for a reversibly operable door, such as a garage door, includes a frame and a carriage movably mounted on the frame and attached to a door for moving the door between open and closed positions. A flexible drive member, such as an endless chain, extends on the frame and is capable of moving the carriage. A drive train is on the frame connected for moving the flexible drive member. A motor housing is mounted on the frame within the motor housing and connected to the drive train. The motor has a shaft extending from the motor housing and engaging the drive train. A bearing assembly that includes metal thrust bearings is on the shaft adjacent to the motor. The metal thrust bearing assembly increases the performance of the electric motor, and thus provides a more powerful motor without changing to a larger motor or otherwise modifying the motor design. The motor is mounted on the frame so as to allow the shaft freely to move axially relative to the motor to permit the shaft to self-align.

Abstract: An improved switch assembly for an electrical appliance is provided which is easily manipulated when the appliance assumes a variety of operating modes. The switch assembly includes a slidably mounted control unit for opening and closing a switch, the latter being concealed within a housing for the appliance and disposed within an electric circuit for the appliance. The control unit is provided with a plurality of exposed, finger-engageable surfaces to effect selective movement of the unit.

Abstract: A screw and guide rail coupling assembly is for a garage door operator. The garage door operator has a motor-driven rotatable screw at least partially within a nonrotatable guide rail and a slide guided by the guide rail and movable longitudinally therealong by engagement with the screw and connectable to open and close the garage door. The screw is in at least first and second screw parts, and a screw coupling is adapted to interconnect adjacent ends of the first and second screw parts. The guide rail is in at least first and second guide parts, and a guide coupling adapted to interconnect adjacent ends of the first and second guide parts. The screw coupling is longitudinally spaced or offset from the guide coupling wherein the screw coupling is completely contained and supported within one of said first and second guide parts. The offset provides a significant increase in the maximum torque of the screw and guide rail coupling assembly.